This research is concerned with the perception and processing by normal humans of visual stimulus structure, that is with the relations between attributes of stimuli and total configurations of stimuli. Three major areas of research are: (1) The effect of configural goodness on information processing speed, using both dot patterns and line patterns which vary in configural goodness, and with classification and comparison tasks. (2) The role of different types of dimensions in both comparison and classification, with dimensions varying in the extent to which they consist of simple physical properties of stimuli. (3) The nature of processing of contingent stimulus dimensions, those in which one dimension specifies which other dimensions or which levels of dimensions are to be further processed.